WASHINGTON (CNN) – In a major departure from previous policy, the United States will join direct talks between U.N. and European powers and Iran over Tehran's nuclear program, the State Department announced Wednesday.

The Obama administration has asked the European Union's international policy chief, Javier Solana, to invite Iran to new talks with the permanent members of the U.N. Security Council and Germany, State Department spokesman Robert Wood said.

Washington, which does not have diplomatic relations with Iran, has stayed out of those talks to date.

"If Iran accepts, we hope this will be an occasion to seriously engage Iran of how to break the logjam of recent years and work in a cooperative manner to resolve the outstanding international concerns about its nuclear program," Wood said.

Iran has so far refused Security Council demands to halt its production of enriched uranium, which it has said will be used to fuel nuclear power plants. The United States has accused Tehran of concealing efforts to develop a nuclear bomb, and the U.N.'s nuclear watchdog agency said it has failed to resolve questions about the aim of Iranian program.

Wednesday's announcement is the latest step in the Obama administration's efforts to engage the Islamic republic diplomatically after nearly three decades without formal ties. Iran has so far responded coolly to the American overtures.